We are in a very important month for people raising several of the major Midwest crops. Now is when the plants have to extract minerals and water from the soil and recent rains, CO2 from the atmosphere and gather photons from the sun to create photosynthates which get sent to the kernels or seeds, increasing seed size and adding grain weight.

We have to hope for additional moisture, lots of sunshine, cool nights and great plant health to help the plants stay green until their normal maturity date.

It is difficult to accurately guess how the season will finish out and if the corn kernels and soybean seed will reach their normal seed size. Currently, many of the fields in the southern three-fourths of the state look good to excellent.

The early weather forecasts for August and through the mid-September time period center on much hotter and drier conditions. These would have shortened the fill period and been a negative for grain yields.

Those predictions may not be accurate if the high temps later in the week are in the 70s. By Aug. 9, we will get a peek into the fall GDU accumulations.

I have been asked by different people and groups what we can expect for national yields. I have to say that gauging yields at this time is difficult.

One negative which became highly visible from the roads was that many corn fields contain plants that are yellowing in the upper leaves. One of the obvious reasons has to be a loss of nitrogen from the constantly saturated soil from both leaching and denitrification. The fields which received Y-dropped nitrtogen or urea granules show a darker green color.

Then there are other fields that show a different yellowish color which in the past progressed into a cannibalization of the protein in the upper leaves When this begins to appear, it often turns into the situation where the plant begins to die early from the top and bottom.

When I traveled along U.S. Highway 20 viewing crops toward Sioux City, it was very apparent that the decline was beginning in flatter topography fields and was also showing up in fields with more slope. The areas with sidehill slopes were also affected.

The disease situation in corn

As we begin to see more foggy days where low laying fields have dews which can last into the afternoon, we can expect to see more leaf diseases. The first two which are being identified more and are increasing in incidence are Northern Corn Leaf Blight {NCLB) and different leaf rusts. The NCLB lesions, which have the appearance of an elongated cigar, are seen in more fields. Hybrids which have B37 backgrounds are more susceptible to both rust and NCLB. Moist conditions and longer lasting dews are going to be favorable to their appearance, whereas hotter and drier conditions reduce the disease threats.

The rust we see more in the northern cornbelt is referred to as common rust. Its lesions are raised and can be on both the top and bottom sides of the leaves.

The second species of rust, which can move in rapidly from southern locales is Southern Rust. Many cornfields to our south and east now show signs of the disease as the spores were transported a few weeks ago by Hurricane Beryl. If and when the Southern rust gets established in an area, the lesions can seem to cover the leaves very quickly and should be treated with a curative, systemic fungicide or mineral mix.

There was a field day near Story City by one of the major fungicide firms last week. The crowd in attendance were from all regions of the state. They showed the parts of the state and the counties where tar spot has already been identified.

Soybean status

With the average bean field having been planted later than hoped, there are many differences in development stages. The growth stages vary from having closed the rows to fields where the plants are still less than 12 inches tall. Most plants added height when the 80-degree Fahrenheit temps arrived.

Where the yields can be influenced is with foliar applied minerals. As the soils dry, the rate of mineral released is reduced. And if the pod number is high, the vascular bundle may not be capable of translocating enough minerals to maximize seed size. That is where foliar applied nutrition needs to be utilized.

Soybean diseases

Once August arrives, we tend to see more foggy mornings where there is lots of dew on the leaves.

This is when diseases such as downey mildew, Septoria and Cercospora increase in incidence and severity. Septoria is the fungus which causes the lower leaves in the canopy to turn yellow, develop brown spots and abscise early. The normal effect is to lower yields by five to seven bushels per acre.

The downey mildew appears as small yellow irregular shaped lesions to form. When you look at the underside of the leaves with a hand lens, you will see small hairs or sori growing from those lesions. There are two types of Cercospora, sojina and Kukuchi. One forms small lesions and the other makes the leaves take on a brown leathery appearance.

Realize that basically fungi are plants that do not have chlorophyll, so they cannot make sugars. Instead they have to steal sugars from plants that can form sugar.

We had a group of 14 Brazilian ag people here in late July. They were mostly from the state of Mato Grosso and included farmers, entomologists and crop consultants. An old friend, Eros Francisco, who I met years ago when he was the top agronomist with the Mato Grossso Research Foundation, or Fundacao MT, is now the State of Alabama and Auburn University extension agronomist.

Their goal was to attend the Hefty Field day held near Sioux Falls. They also wanted to visit with a few Iowa growers to see and learn about ag here and how they manage their crops.

The farms we visited include those of Jeremy Gustafson of Boone, Steve Kaltenhauser of Ames, and Tim Couser of Nevada. I would like to thank them for being gracious hosts.

When we were at Couser’s, they had their two drones at work applying an insecticide to help control Japanese beetles. If you have never seen a team of two drones working off a twin-leveled truck equipped as a command center complete with a large generator to constantly charge the batteries, you need to do so. The two guys in charge stayed constantly busy refilling the drone’s tank, running the air controllers and charging and loading full batteries. This job will change dramatically once a company builds a larger drone powered by an engine.

The use and value of drones is poised to become more popular for several reasons. They can cover up to 400 acres per day. Their $25,000 to $27,000 cost for each is a lot less than a high clearance sprayer. They won’t run down any plants. They can run when the ground is too wet for a ground rig. And they can fly over crops which have been goosenecked by winds or insect damage or a field where power lines or trees make aerial applications with an airplane difficult or impossible. And they make a lot less noise and attract a lot less commotion than an airplane when a field next to houses needs to be sprayed.

One pertinent question is ‘do they do a better job of application than does an airplane, which causes a draft which drives spray droplets into the crop canopy?’ or a ground rig.

To me the answer depends to a great degree on the property of the product being applied.

Are the products curative and systemic? If they are not, then timing of application is critical, as once the targeted pathogen has invaded the plants, the triazoles and strobes will not be effective. And if the products are not systemic, coverage and gallonage are critical. One other sticking point is that both airplane pilots and drone applicators are asking about the long-term health effects from their constant exposure to products which carry a strict warning label. The future as I see it is a move away from the fungicides we now use to mineral-based products, which work by stimulating a plant’s immune system. A number of them carry no warning label and are actually OMRI certified.

In addition to note, if you did not read the column by Alison Robertson in the July 1 copy of the Wallace’s Farmer magazine, look it up. The problem she dwells on is that there are more fungi that are able to attack plants, animals and humans. In some cases, the infections are serious and can be fatal. Plus, in most cases, the human medicines used to treat the patients are members of the triazole family, and those medicines are no longer effective.